1. Field of the Invention
The invention relates to a method for processing fish fillets, and, in particular, to the separation of a superficial layer containing skin, and also to an apparatus comprising a conveying roller with a skid-resistant or gripping surface, a pressing shoe having a pressing surface facing the conveying roller surface, the pressing shoe being positioned to leave a narrow gap between its pressing surface and the conveying roller surface, and a cutting mechanism comprising a first knife having its cutting edge lying near to the surface of the conveying roller and a second knife having its cutting edge lying remote from the surface of the conveying roller.
2. Prior Art
An apparatus is known from U.S. Pat. No. 4,628,806, which comprises a conveying roller, whereby the conveying roller surface is arranged to lie opposite the cutting edges of two knives spaced at different distances. The apparatus is furthermore provided with a pressing shoe having a pressing surface spaced from the surface of the conveying roller. The cutting edge of the more closely spaced first knife is integrated in the pressing shoe as a rigid component thereof. The further spaced second knife is also rigidly formed in the same manner. A conveyor is located both in front of and above the conveying roller for feeding the material to be processed or for supporting the conveying of the same. After the initial cut of the first knife, the conveying roller ensures in cooperation with the pressing surface that the rind is drawn away as the separation proceeds.
This apparatus is designed for removing rind from fat. In this process, the second knife has the task of removing a layer which comprises the rind and a layer of fat, while the first knife is provided to separate the rind from the fat layer. The course of this process is such that first the second knife and then the first knife come into operation.
An apparatus of this kind is not at all suitable for the corresponding processing of fish fillets. This is due particularly to the lack of stability of shape and the soft consistency of such fillet product. These characteristics necessitate that at least the separating cut made in the muscle meat is carried out by drawing cutting, for example by means of a knife driven to oscillate. Such a knife is shown in DE 37 00 324, for example.
On employing such a knife it is essential, and a more or less unconditional prerequisite, that, at least in the processing area, the fish lies flat, i.e. not compressed and fold-free, in order to avoid irregularities, like patches of skin, occurring which reduce the quality of the finished product. This is intended to be achieved by means of drawing conveying, as is also shown in DE 37 00 324, to which end there is employed a pressing shoe with a pressing surface which forms a conveying gap together with the skinning roller, through which the severed surface layer is pulled away after separation.
This will function only so long as the surface layer to be separated relates to the relatively tough skin, which allows a correspondingly strong hold in said conveying gap. If, however, muscle meat is to be cut, as is often required for the purpose of separating a fat layer or a layer of dark meat, for instance, this process fails because the soft consistency of such a surface layer does not ensure secure conveying due to lack of grip.
3. Objects of the Invention
A first object of the invention is to suggest an improved separating method for severing a surface layer with skin, which avoids the above mentioned drawbacks.
A further object of the invention is to provide a separating method for severing a surface layer of any desired thickness.
A still further object of the invention is to suggest an apparatus for carrying out such a method in an economic manner.